Gonads to Gametes Flashcards
What type of offspring does asexual reproduction result in?
Genetically identical
Give an example of asexual reproduction
mitosis at interphase
What is Parthenogenesis
Parthenogenesis is a natural or artificial process in which an embryo develops from an unfertilized egg, without the need for fertilization
Name 2 species that do parthenogenesis
Bees and lizards
What is the result of sexual reproduction?
genetically varied offspring
What process causes genetic variation seen in sexual reproduction
meiosis
How are haploid cells made?
-Crossing over
-2 sequential divisions
How many haploid cells are needed to make a diploid cell?
2
What does natural selection depend on?
-Sperm and egg coming together
-Mate selection (culture)
Describe the High energy investment in gametes as a fertilisation strategy
-Aquatic species
-spawn, make gametes
-maximise the likelihood of their offspring surviving
-Higher parental investment further down the line
How many eggs do human females ovulate?
1
Describe the low energy investment strategy in gamete production
-mammals
- 1 egg ovulated
-fertilised internally which is safer than externally, however fewer eggs are produced
-Higher parental burden down the line
How many oocytes are produced whilst the ovary is developing in the embryonic period, and what is the number at birth?
-7 million during the embryonic period
- 0.5 million at birth
Why does the number of oocytes decrease so suddenly from the embryonic period to birth?
Thought to be an evolutionary process from a species prior to humans that used to spawn.
What is an oviparous animal?
An animal that produces young by laying eggs which are hatched after being laid by a parent, like a bird
What type of fertilisation do oviparous animals do?
Internal
Give an example of an oviparous animal
Chicken
What is the consequence of oviparous fertilisation?
-larger eggs to support development
-the babies develop quicker due to there being lots of nutrition available
How often do chickens ovulate?
-every day, regardless of fertilisation
What types of animals are viviparous?
-mammals and humans
How large are the eggs of viviparous animals? What are the consequences of this?
-Small
-most nourishment is from the mother
slower development
-the mother requires an adaptive reproductive tract to cope with the fertilisation, the gestation and the birth
What does it mean if an animal is altricial?
They’re helpless from birth
What does it mean if an animal is precocial?
the animal is active and able to move freely from hatching
What 6 factors must be considered in reproduction?
Gamete selection, mate selection, coordination, selective pressure, successful birth and parental care
When does the reproductive lifecycle begin?
puberty
How does a male’s reproductive capacity change with age?
slow decline with age
When does a female’s reproductive capacity end?
menopause
Roughly what is the fertility rate in the age group 20-24?
86%
When does female fertility decline massively?
in the 40’s
What is the probability of pregnancy at 50?
1%
